Romney's victory over Obama in Plymouth County ywas a result of 8,577 votes compared to 4,148 for Obama.
The Republican winning trend went throughout all election results in the county.
Incumbent Congressman Steve King, of Kiron, won a sixth term by defeating his Democratic opponent, Christie Vilsack, of Ames.
King had 53.04 percent of the votes in the 39 counties of the Fourth Congressional District while Vilsack had 44.76 percent.
In Plymouth County, King had two-thirds of the total vote.
The total number of votes for King in the county was 8,596 compared to 3,957 for Vilsack.
In state offices, incumbent State Rep. Chuck Soderberg, R-Le Mars, was unopposed in his re-election bid.
Plymouth County voters eligible to cast ballots for the District 5 House seat backed Soderberg with 99 percent of the vote for a total of 9,686 votes.
In the entire Fifth District, Soderberg received 11,981 votes or 99 percent of the 12,060 votes cast.
State Senator Randy Feenstra, R-Hull, received 348 votes from the portion of the senate district that is in Plymouth County.
Of the 26,049 votes cast in the Senate District 2, Feenstra received 25,953 or 99 percent of the unofficial vote total.
Voters in eastern Plymouth County re-elected State Rep. Dan Huseman, R-Aurelia, with 358 votes.
Overall, Huseman received 12,433 votes for the District 3 House seat or 99 percent of the 12,480 votes cast.
Iowa voters have retained state Supreme Court Justice David Wiggins, who faced opposition because he supported a 2009 ruling that legalized gay marriage in Iowa.
Statewide, Wiggins earned 54 percent of the vote, but in Plymouth County the majority of voters rejected Wiggins retention on the state's high court.
There were 4,393 'yes' votes compared to 5,343 'no' votes, based on unofficial election results.
A Le Mars man, Robert Dull, was retained as a district associate court judge. Dull received 79 percent of the total vote.
Five Republican Plymouth County elected officials were unopposed in the general election.
Plymouth County Auditor and Election Commissioner Stacey Feldman was supported by 9,948 voters in her re-election bid for auditor.
Sheriff Mike Van Otterloo garnered the highest vote of county elected officials with 10,532 votes.
That was followed by 9,988 votes for District 2 Supervisor Mark Loutsch and 9,858 votes for District 5 Supervisor Jim Henrich.
District 3 Supervisor Don Kass, of Remsen had 9,810 votes.
Voter turnout for the general election in Plymouth County was approximately 600 more than the 2008 presidential election, according to Feldman.
"This was the highest percentage of voter turnout in Plymouth County in recent years, if not in history," she said.
She attributed the large participation to the Romney-Obama race.
"Obviously, it's the presidential election which encourages and brings out the record number of voters," Feldman said.
Approximately 13,000 people voted in Plymouth County, she said.
The absentee vote total of 5,538 also set a new record for the general election, according to Feldman.
Approximately 300 absentee ballots had not been returned yet.
Results of the election in Plymouth County are unofficial until the board of supervisors reviews results next Tuesday.
A complete precinct-by-precinct report for Plymouth County will be published in Thursday's edition.